DESCRIPTION: The proposed research will investigate the hypothesis that green tea catechins are versatile antioxidants capable of preventing oxidative damage by diverse oxidants in biological systems. The investigators will 1) identify products of green tea catechins (EGCG, EGC, and ECG) reaction with peroxyl radicals, hydroxyl radicals, peroxynitrite, and singlet oxygen in chemically defined model systems; 2) develop sensitive assays for specific reaction products indicative of the antioxidant reactions; 3) characterize antioxidant reactions of the catechins in mouse skin treated with tumor promoters and UVB in vivo.